EP0339873B1 - Vorrichtung und Verfahren zum Messen der elektrischen Eigenschaften von Materialien - Google Patents

Vorrichtung und Verfahren zum Messen der elektrischen Eigenschaften von Materialien Download PDF

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Publication number
EP0339873B1
EP0339873B1 EP89303946A EP89303946A EP0339873B1 EP 0339873 B1 EP0339873 B1 EP 0339873B1 EP 89303946 A EP89303946 A EP 89303946A EP 89303946 A EP89303946 A EP 89303946A EP 0339873 B1 EP0339873 B1 EP 0339873B1
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EP
European Patent Office
Prior art keywords
microwave
waveguide
sheet
slit
intensity
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Expired
Application number
EP89303946A
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English (en)
French (fr)
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EP0339873A1 (de
Inventor
Shigeyoshi Osaki
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Kanzaki Paper Manufacturing Co Ltd
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Kanzaki Paper Manufacturing Co Ltd
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Publication date
Application filed by Kanzaki Paper Manufacturing Co Ltd filed Critical Kanzaki Paper Manufacturing Co Ltd
Publication of EP0339873A1 publication Critical patent/EP0339873A1/de
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N22/00—Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more

Definitions

  • the present invention relates to an apparatus and method for measuring electric characteristics of material by applying electromagnetic microwaves.
  • GB-A-2 050 664 discloses measuring of electric characteristics of sheet-like materials, wherein an unguided bean of microwave radiation is generated, the sheet-like material is placed in the path of the bean, and the microwave radiation transmitted through the material and the microwave radiation reflected by the material are measured.
  • JP-A-61 204 549 (abstracted in Patent Abstracts of Japan, vol. 11, no. 35(P-542) [2482] 3rd February 1987) and EP-A-0 175 182 disclose apparatus for measurement of a characteristic of a sample or article by means of microwave radiation where waveguides are used to direct the microwave energy to the sample or article and to direct microwave energy from the sample or article.
  • An object of the invention is to provide apparatus which is capable of easily and simply measuring the conductivity of conductive material by means of microwaves.
  • Another object of the invention is to provide novel and effective method for detecting the above measurement by means of microwaves.
  • an apparatus for measuring electric characteristics of sheet-like materials comprising: a main waveguide in the form of a straight tube for guiding a microwave therein; means connected to one end of said main waveguide, for introducing the microwave thereto; a slit formed across an intermediate portion of said waveguide between said one end and the other end of said waveguide for accomodating a sheet-like material, an electric characteristic of which is to be measured; first detector means connected to said other end of said main waveguide for detecting a transmitted microwave through the sheet-like material ted in said slit; an auxiliary waveguide connected at one end thereof to a directional coupler located on the wall portion of said main waveguide adjacent to said slit at the microwave in side for admitting the microwave from said main waveguide; and second detector means connected to the other end of said auxiliary waveguide for detecting a reflected microwave from the sheet-like material accomodated in said slit; whereby said electric characteristic of the sheet-like material is determined from the
  • a method for measuring electric characteristics of sheet-like materials using an instrument which includes a main waveguide in the form of a straight tube having one end connected to means for introducing a microwave into said main waveguide and having the other end connected to first microwave detector means a slit formed across an intermediate portion of said waveguide between said ends thereof, and an auxiliary waveguide branching from the wall portion of said tube adjacent to said slit with the branch-extension end being associated with second microwave detector means, said method comprising the steps of: inserting a sheet-like material, an electric characteristic of which is to be measured, into said slit; energizing said microwave introducing means to generate a microwave in said tube member and to direct it onto the sheet-like material in said slit; detecting a transmitted microwave passing through the sheet-like material by said first detector means; detecting a reflected microwave entering said auxiliary waveguide from said sheet-like material by said second detector means; and determining an electric characteristic of the sheet-like material in accordance with
  • an apparatus 10 embodied by the invention is provided with an antenna or probe 12a of a driving circuit as microwave-introduction means 12 at the left-end as shown of the waveguide 11 and also with a slit 13 which traverses the waveguide 11 in the halfway at a distance of the substantial length of the waveguide 11 from the left-end for allowing insertion of the specimen through it.
  • An auxiliary waveguide 14 is secured on the left or major portion of slit 13 shown in FIG.1, i.e., the auxiliary waveguide 14 is connected through a directional coupler 15 to the side at which microwave is irradiated to the specimen.
  • Wave detectors 16 and 17 are respectively provided at the ends of the waveguides 11 and 14.
  • any non-reflection material is set to the left end of the auxiliary waveguide 14.
  • any non-reflection material be set to the right end of the waveguide 11 in order that the reflected microwave from the waveguide 11 other than the one 14 corresponding to the wave-detector 17 can be prevented from being detected.
  • the specimen shows extremely large conductivity and metallic characteristic, then its reflection factor rises, whereas the transmission factor and the absorption characteristic diminish to a very low level. Conversely, if the specimen is formed of a good insulating material and shows extremely low conductivity, the reflection factor and the absorption characteristic diminish, and conversely, the transmission factor extremely rises. Thus, if the absorption curve (absorption/conductivity factor) is given, then either the transmission factor or the reflection factor is measured so that the user can derive the non-measured factor from the either of these factors. In this case, only the wave-detector 16 is provided on the wave-permeation or transmitted side without providing auxiliary waveguide 14 (see FIG.
  • the user can execute measuring operations by applying the system which eliminates all the components shown to the right of slit 13 (see FIG. 1).
  • the right end of the substantial tube body of the waveguide 11 is open, and thus, reflected microwave is present on the open surface even when no specimen is set.
  • the open surface of the right-end of the substantial tube body of the waveguide 11 is covered with a conductive specimen, if the conductivity is very high, the reflection factor extremely rises.
  • the refleciton factor approximates the value which is present when the right end of the waveguide tube body is open. This allows the user to properly measure the conductivity of the specimen.
  • the inventors When providing the slit 13 within the waveguide 11 as shown in FIG. 1, into which the specimen is inserted, the inventors first checked to see if the position of the slit 13 could adversely affect the propagation of microwave inside of the waveguide 11, or not.
  • the inventors fixed the length of the left part of the waveguide 11 shown in FIG. 1 to be 1 meter from the position of slit 13 having 1.9mm of width.
  • the inventors then varied the length of the right part of the waveguide 11 in a range from 1cm to a maximum of 20cm. As a result, the inventors confirmed that the level of signals output from the wave detector remained almost constant.
  • inventors then fixed the length of the right part of the waveguide 11 to be 10cm from the position of the slit 13, and then varied the length of the left part in a range from 10cm to a maximum of 150cm. Like the above case, inventors confirmed that the level of signals output from the waveguide 11 did not vary at all. The inventors then varied the width of the slit 13 in a range from zero to a maximum of 7mm. When the slit 13 was provided with 7mm of the width against 0mm of the reference, the level of signals output from the wave-detector 16 is lowered by 6.5dB. It proves that the narrower the width of the slit 13, the better the stability of the signal level output from the wave-detector 16. This is probably because microwave leaks through the slit 13 simultaneous with the reflection of microwave caused by presence of slit 13.
  • the inventors Based on the constitution as shown in FIG. 1, the inventors assembled the apparatus composed of the main waveguide with a size of 29.1mm x 58.1mm and a slit with a width of 4mm. The inventors inserted a specimen sheet made from poly(ethylene terephthalate) fiber with a thickness of 100 microns into the prepared slit. Finally, the inventors confirmed by comparison with the output signal level prior to the insertion of the specimen that the level of signals output from the wave-detector 16 remained constant.
  • the test for the second example was executed by means of the same apparatus as that was used for the first example.
  • the inventors prepared a specimen sheet made from non-woven carbon-fiber cloth with a weight of 34.6g./m 2 , and then inserted the specimen into the slit.
  • the inventors then checked the level of signals output from the wave-detectors 16 and 17 at some directions by rotating the specimen in its plane. The test result is described below.
  • the inventors set angles of the rotation of the specimen based on the direction of the short-part of the waveguide 11, i.e., in the direction of the electric field.
  • the test for the third example was executed by means of the same apparatus as that was used for the above examples with an exception in which the right part of the waveguide 11 was disengaged from the slit 13 to provide an open-end surface for the substantial tube body of the waveguide 11.
  • the inventors checked the conductivity of the organic conductive sheet made from a non-woven carbon-fiber cloth inserted in plastic films, where the specimen in a plastic film fully covered the open-end of the waveguide 11.
  • the inventors set a dielectric sheet by pressing it against the back of the specimen for stabilizing it. Since a part of microwave transmitted through the specimen, it is essential for the system to stabilize means for tightly pressing the specimen against the open-end of the waveguide tube body because the stability of the specimen critically affects the measurement of the reflected microwave.
  • the test result of the third example is shown below. Like the above case, the inventors confirmed that non-woven carbon-fiber cloth had distinct fiber-orientation characteristic.
  • the user can easily set the specimen to the apparatus having the structure mentioned above, and thus, the user can execute measurement against a web without cutting off a specimen from it.
  • the apparatus embodied by the invention allows the user to execute measurement not only against sheet-like material, but he can also do it against a thick object as well. Furthermore, the apparatus allows the user to execute measuring operations by bringing the open-end of the waveguide into contact with the surface of a structured object or across the predetermined minimal clearance.
  • the apparatus allows a user to easily measure the conductivity and the anisotropy of conductive materials like conductive plastic objects.
  • the user can easily insert the specimen into the apparatus by bringing the specimen into contact with the open end of the waveguide tube, and yet, the user can easily rotate the specimen as required.
  • the apparatus embodied by the invention offers useful advantage in allowing the user to measure electric characteristic of those specimens formed of an web and/or a solid body composition and those specimens having substantially wide area without the need for cutting off the specimen from them.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Claims (2)

  1. Vorrichtung zum Messen elektrischer Eigenschaften bogenartiger Materialien, welche folgendes umfaßt:
    Einen Hauptwellenleiter (11) in Form einer geraden Röhre zum Leiten einer Mikrowelle in derselben;
    eine mit einem Ende des Hauptwellenleiters verbundene Einrichtung (12, 12a) zum Einführen der Mikrowelle in diesen;
    einen quer über einem Zwischenbereich des Wellenleiters zwischen dem einen Ende und dem anderen Ende des Wellenleiters gebildeten Schlitz (13) zur Unterbringung eines bogenartigen Materials, von dem eine elektrische Eigenschaft gemessen werden soll;
    eine mit dem anderen Ende des Hauptwellenleiters verbundene erste Erfassungseinrichtung (16) zur Erfassung einer durch das in dem Schlitz untergebrachte bogenartige Material übertragenen Mikrowelle;
    einen Hilfswellenleiter (14), der zum Einlassen der Nikrowelle vom Hauptwellenleiter an seinem einem Ende mit einem Richtungskoppler verbunden ist, welcher an dem neben dem Schlitz an der Mikrowellen-Einführungsseite liegenden Wandbereich des Hauptwellenleiters angeordnet ist; und
    eine mit dem anderen Ende des Hilfswellenleiters verbundene zweite Erfassungseinrichtung (17) zur Erfassung einer von dem in dem Schlitz untergebrachten bogenartigen Material reflektierten Mikrowelle;
    wobei die Bestimmung der elektrischen Eigenschaft des bogenartigen Materials aus der Beziehung zwischen einer Eingangs-Mikrowellenintensität und ihrer durch den Bogen übertragenen Intensität und/oder zwischen der Eingangs-Mikrowellenintensität und ihrer vom Bogen reflektierten Intensität erfolgt.
  2. Verfahren zum Messen elektrischer Eigenschaften von bogenartigen Materialien mit einem Instrument, welches folgendes umfaßt: Einen Hauptwellenleiter in Form einer geraden Röhre, deren eines Ende mit einer Einrichtung zur Einführung einer Mikrowelle in den Hauptwellenleiter verbunden und deren anderes Ende mit einer ersten Mikrowellen-Erfassungseinrichtung verbunden ist, einen quer über einem Zwischenbereich des Wellenleiters zwischen dessen Enden gebildeten Schlitz, und einen Hilfswellenleiter, der von dem neben dem Schlitz liegenden Wandbereich des Röhrenglieds abzweigt, wobei das von der Zweigstelle entfernte Ende der Abzweigung einer zweiten Mikrowellen-Erfassungseinrichtung zugeordnet ist, wobei das Verfahren die folgenden Schritte umfaßt:
    Einschieben eines bogenartigen Materials, von dem eine elektrische Eigenschaft gemessen werden soll, in den Schlitz;
    Erregen der Mikrowellen-Einführungseinrichtung zur Erzeugung einer Mikrowelle in dem Röhrenglied und zum Führen derselben auf das in dem Schlitz befindliche bogenartige Material zu;
    Erfassen einer übertragenen, durch das bogenartige Material passierenden Mikrowelle durch die erste Erfassungseinrichtung;
    Erfassen einer reflektierten Mikrowelle, die von dem bogenartigen Material aus in den Hilfswellenleiter eintritt, durch die zweite Erfassungseinrichtung; und
    Bestimmen einer elektrischen Eigenschaft des bogenartigen Materials gemäß der Beziehung zwischen einer Eingangs-Mikrowellenintensität der Einführungseinrichtung und der Intensität der vom Material reflektierten Mikrowelle, und zwischen der Eingangs-Mikrowellenintensität und der Intensität der durch das Material übertragenen Mikrowelle.
EP89303946A 1988-04-22 1989-04-20 Vorrichtung und Verfahren zum Messen der elektrischen Eigenschaften von Materialien Expired EP0339873B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP63100999A JPH01270648A (ja) 1988-04-22 1988-04-22 材料の電気的特性測定装置
JP100999/88 1988-04-22

Publications (2)

Publication Number Publication Date
EP0339873A1 EP0339873A1 (de) 1989-11-02
EP0339873B1 true EP0339873B1 (de) 1992-10-07

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US (1) US5001433A (de)
EP (1) EP0339873B1 (de)
JP (1) JPH01270648A (de)
DE (1) DE68903128T2 (de)

Families Citing this family (8)

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US5132903A (en) * 1990-06-19 1992-07-21 Halliburton Logging Services, Inc. Dielectric measuring apparatus for determining oil and water mixtures in a well borehole
US5256978A (en) * 1992-04-27 1993-10-26 Mitchell Rose Microwave moisture content analyzer
US5508622A (en) * 1994-12-14 1996-04-16 Gatzlaff; Harold Coating defect detector system
JP3731314B2 (ja) * 1997-03-28 2006-01-05 王子製紙株式会社 配向測定装置
JP2006300828A (ja) * 2005-04-22 2006-11-02 Kindai Techno Corp プリプレグに内在する導電性微小粒子物質の検出装置
US7288944B1 (en) 2005-07-11 2007-10-30 The United States Of America As Represented By The Secretary Of The Navy Evanescent waveguide apparatus and method for measurement of dielectric constant
US7894765B2 (en) * 2006-12-18 2011-02-22 Canon Kabushiki Kaisha Sheet processing apparatus and image forming apparatus for controlling a folding operation
CN110389135A (zh) * 2019-07-18 2019-10-29 成都飞机工业（集团）有限责任公司 一种反射率测试集成微波探头

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Publication number Publication date
DE68903128T2 (de) 1993-02-11
EP0339873A1 (de) 1989-11-02
DE68903128D1 (de) 1992-11-12
JPH01270648A (ja) 1989-10-27
US5001433A (en) 1991-03-19

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